Peer-reviewed veterinary case report
Myosin heavy-chain myopathy in 2 American quarter horses.
- Journal:
- Veterinary pathology
- Year:
- 2024
- Authors:
- Faccin, Mayane et al.
- Affiliation:
- Texas A&M University · United States
- Species:
- horse
Plain-English summary
Two young American quarter horses, a 1.5-year-old gelding and an 11-month-old filly, were brought to the vet because they suddenly started limping and seemed very tired. The gelding also had a runny nose, while the filly was losing muscle quickly. Blood tests showed high levels of a substance called creatine kinase, which indicates muscle damage. Both horses had similar muscle inflammation and damage, and additional issues were found in each horse, including an infection in the gelding and a lung abscess in the filly. Genetic tests confirmed they both had a specific mutation linked to a muscle condition called myosin heavy-chain myopathy, and it seems that bacterial infections may have contributed to their problems. The treatment approach is still being evaluated, but the underlying muscle condition has been identified.
Abstract
A 1.5-year-old American quarter horse gelding (case 1) and an 11-month-old American quarter horse filly (case 2) were presented for acute onset pelvic lameness and lethargy. Case 1 had nasal discharge, while case 2 developed rapid muscle atrophy. Both horses had elevated serum creatine kinase activity. The horses showed similar polyphasic histiocytic and lymphoplasmacytic myositis with necrosis, mineralization, and regeneration. Additionally, case 1 hadsubsp. e-induced suppurative retropharyngeal lymphadenitis with renal purpura hemorrhagica and myoglobinuric nephropathy. A focal pulmonary abscess caused bywas found in case 2. Genetic testing revealed case 1 as heterozygous and case 2 as homozygous for the E321Gvariant, supporting the diagnosis of myosin heavy-chain myopathy, with concomitant bacterial disease as potential triggers.
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Search related cases →Original publication: https://pubmed.ncbi.nlm.nih.gov/37818977/